Welcome to HCM
After reading what you have described is you may be having irregular beats in medical terms VPC that is extra systole
It would be advisable to check with a cardiologist and get a ECG to know the cause.
Then a detail cardiac work up including 2 D Echocardiography
and Holter Monitoring may be required to trace the exact cause and treat it
In the mean time avoid smoking
and excess of tea and cofee.
Just relax and get your check up as soon as possible.
Good luck to you